1. Field of the Invention
The present invention relates to a television receiver and a signal processing apparatus, both for processing a video signal using a programmable operation unit and a microprocessor unit (hereinafter referred to as MPU).
2. Description of the Prior Art
In recent years, broadcasting systems have been diversified and, at present, not only conventional NTSC television broadcasting utilizing a ground wave but also high-definition television broadcasting utilizing a broadcasting satellite (hereinafter referred to as BS) are put to practical use. With the diversification of broadcasting systems, television receivers are required to have the ability to receive various broadcasts.
FIG. 9 is a block diagram illustrating a television receiver receiving a conventional NTSC system television broadcast using a ground wave, an NTSC broadcast using a BS, and a high-definition television broadcast using a BS.
First of all, the operation of the television receiver to receive the ground wave television broadcast will be described.
A conventional television broadcasting wave, i.e., a ground wave, received by an antenna 10 is input to a V/UHF tuner, wherein a desired channel signal is selected and converted into an intermediate frequency signal. Thereafter, the intermediate frequency signal is amplified by an intermediate frequency amplifier 12, converted into a base band NTSC signal by a VSB demodulator 13, and supplied to a selector circuit 24. In the selector circuit 24, the base band NTSC signal from the VSB demodulator 13 is selected, and this signal is input to a synchronous processing circuit 15 and an AD converter 14. In the NTSC system, the sampling frequency of the AD converter 14 is usually four times as high as a color subcarrier, and it is about 14.3 MHz. The base band NTSC signal digitized by the AD converter 14 is supplied to an NTSC decoder circuit 16, wherein the signal is subjected to the NTSC decoding process, such as luminance signal/chrominance signal separation, color demodulation, and inverse matrix processing. As a result of the NTSC decoding process, RGB signals are output from the decoder circuit 16. These RGB signals are converted into analog signals by a DA converter 17, selected in a selector circuit 20, transmitted through a driver circuit 21 to a CRT 22, and displayed as a video image.
On the other hand, in the synchronous processing circuit 15, a horizontal synchronous signal and a vertical synchronous signal are reproduced from the input base band NTSC signal, and a clock signal synchronous with the input signal is produced. The synchronous signals and the clock signal are input to the NTSC decoder circuit 16, the AD converter 14, the DA converter 17, and a deflection processing circuit 18, and these circuits are operated according to these signals.
The deflection processing circuit 18 generates a deflection control signal on the basis of the synchronous signals from the synchronous processing circuit 15. The deflection control signal is a sawtooth waveform signal for horizontal and vertical deflections, and this signal is selected in a selector circuit 23 and controls deflection of the CRT 22.
A description is now given of the operation of the television receiver to receive a high-definition television signal. High-definition television broadcasting currently being put to practical use employs MUSE (Multiple Sub-Nyquist Sampling Encoding) system which is described by Ninomiya et al. in MD-TV Broadcasting System Using Single Channel Satellite (MUSE), Technical Report of Television Society TEBS 95-2, Vol.7, No. 44. In this system, a broad-band and high-definition video signal is subjected to 4:1 sub-nyquist sampling which makes one round by four fields, whereby the video signal is compressed to about 1/4. Employing the MUSE system, FM (Frequency Modulation) satellite broadcasting is implemented.
Initially, a high-definition television broadcasting wave received by an antenna 30 is input to a BS tuner 31, wherein a desired channel signal is selected and converted into an intermediate frequency signal. Thereafter, the intermediate frequency signal is amplified by an intermediate frequency amplifier 32 and supplied to an FM demodulator 33. A base band MUSE signal output from the FM demodulator 33 is subjected to sampling at 16.2 MHz by an AD converter 34, and supplied to an MUSE decoder circuit 36 and a synchronous processing circuit 35.
In the MUSE decoder circuit 36, the original broad-band high-definition video signal is reproduced by approximately interpolating sampling point information which has not been transmitted, using intra-field, inter-field, or inter-frame interpolation. The high-definition video signal so reproduced is output as an RGB signal. The RGB signal is converted into an analog signal by a DA converter 37, selected in the selector circuit 20, transmitted through the driver circuit 21 to the CRT 22, and displayed as a video image.
On the other hand, in the synchronous processing circuit 35, a horizontal synchronous signal and a vertical synchronous signal are reproduced from the input base band MUSE signal, and a clock signal and a control signal, which are required for the operation of the MUSE decoder circuit 36, are produced. The synchronous signals, the clock signal, and the control signal are input to the MUSE decoder circuit 36, the AD converter 34, the DA converter 37, and a deflection processing circuit 38, and these circuits are operated according to these signals.
The deflection processing circuit 38 generates a deflection control signal on the basis of the synchronous signals from the synchronous processing circuit 35. The deflection control signal is a sawtooth waveform signal for horizontal and vertical deflections, and this signal is selected in the selector circuit 23 and controls the deflection of the CRT 22.
It is well known that, in satellite broadcasting, not only the high-definition television broadcasting using the MUSE system but also the conventional television broadcasting using the NTSC system are implemented. In this case, the selector circuit 24 shown in FIG. 9 selects a base band NTSC signal output from the FM demodulator 33, and this signal is subjected to the same NTSC decoding process as described above for the ground wave broadcasting.
As described above, the prior art television receiver for both the high-definition television broadcasting and the conventional television broadcasting is equipped with individual processing circuits for the respective broadcasting systems, i.e., the decoder circuits 16 and 36, the synchronous processing circuits 15 and 35, and the deflection processing circuits 18 and 38, as shown in FIG. 9, resulting in an increase in the circuit scale of the television receiver and an increase in the cost.